Currently many developed western economies have aging populations. Improved health care and advanced medical technologies are contributing to longer lives on average. As time passes, more and more people reach an advanced age. With advanced age comes reduced mobility, for example, less ability to get up and down stairs in a family home. A modern trend in managed health care is home care, in which individuals are encouraged to live at home rather than in an institution. Home care generally includes a higher quality of life and can be less expensive. Therefore, there is a growing need for devices to enhance the mobility of seniors and other mobility challenged individuals who wish to remain in their homes, but have difficulty using stairs or the like.
To meet the needs of such persons, motorized devices to lift and lower a person up or down stairways have become more popular. In some configurations, the person sits on a seat which rides on a rail. A motor is used to drive the device up and down the rail. The rail is typically made from metal and the drive mechanism is usually a toothed wheel which engages a rack located in the rail. The motor drives the toothed wheel which then rotates and advances the seat along the rail. In some cases the seat is replaced with a platform, onto which a wheelchair may be driven. Thus, rather than sitting on the seat, the person remains in their wheelchair as the platform is lifted or lowered and then the wheelchair simply rolls off the platform at the end of the journey.
These type of devices have met with significant success, but suffer from a number of drawbacks. As can be appreciated, these devices, among other things tend to permit a mobility challenged person to remain in their own home, even though they may no longer be able to climb the stairs between the upstairs and the downstairs. Thus, there is a class of such devices that are specifically designed to be retrofit into existing structures by being placed, for example on an existing stairway. The racks and rails are typically made from metal, to provide sufficient strength for the rack and pinion style gear drive. Such metal components are heavy and somewhat expensive. Thus, it can be both costly and awkward to ship the material to where it is needed. Its weight also makes it awkward and difficult to install. Further, the drive gear, which is typically part of the moving platform is also heavy and expensive. Weight in the drive gear provides a double liability, because not only is the device more expensive to make and ship, every time the lift device is used more energy is required to lift the heavy gear and motor up and down the rail.
Another problem in the prior art devices is that the motors are typically fairly large. This is due to the need to provide enough power to overcome inefficiencies in the drive system as well as enough lift to first, lift the person with a reasonable margin of safety, then, lift the weight of the platform and or seat, as well as the heavy elements of the drive train including both the motor and the drive gear. In this sense there is a negatively reinforcing cycle in which a heavier drive train requires a heavier motor, which in turn requires more lifting power and again a heavier motor. As a result the prior art devices tend to include expensive and heavy components in the drive train, including the motor itself.